In hospitals and nursing-care facilities, patients and care-receivers may move from their rooms where they lie on a bed to other places more than once a day. For the moving, patients and care-receivers are transferred from their beds to wheelchairs usually manually by nurses or care-givers. Such transferring of patients and care-receivers is a heavy physical burden to the nurses and care-givers.
A bed has been proposed which allows separation of part of a base unit of the bed with a patient or a care-receiver staying thereon so that the separated part can be used as a wheelchair, which reduces the heavy physical burdens of the transferring.
There is an electric wheelchair which allows a user to freely operate the electric wheelchair using a joystick. Furthermore, there is an electric wheelchair provided with a contact sensor which reacts to a hit of the electric wheelchair against another object so that the electric wheelchair can automatically avoid the other object.
Here, use of a plurality of contact sensors has been considered to be effective in allowing the electric wheelchair to move into a narrow lane because the electric wheelchair inevitably comes in contact with objects such as a wall.
In this case, the electric wheelchair can make a smooth move with a setting regarding motional properties (see (Equation 1) for a control law) of the electric wheelchair for each of the contact sensors.[Math. 1]F=M{umlaut over (X)}+D{dot over (X)}  (1)MεR3×3: Apparent mass property of a wheelchairDεR3×3: Apparent viscosity property of a wheelchair{dot over (X)}εR3: Instruction operation velocity of a wheelchair
The smooth move means a move of the electric wheelchair including adjustment of orientation upon contact with another object (reaction of the contact sensors) to avoid further contact with the object (contact avoidance operation and orientation adjustment operation). In addition, the smooth motion also means a quick move of the electric wheelchair upon reaction of the contact sensors in order to lessen an impact on the electric wheelchair.
Such a smooth move (contact avoidance operation and orientation adjustment operation) can be made by appropriately adjusting operation of the electric wheelchair (in three components of x-axis translation, y-axis translation, and z-axis rotation) as a function of contact detected by the contact sensors. Specifically, upon contacting with another object, the electric wheelchair makes a smooth move by lowering the apparent mass property M and the apparent viscosity property D, which are included in the motional properties of the wheelchair in (Equation 1).
Aside from the electric wheelchair, a cleaning robot has been proposed as shown in FIG. 14 (for example, see PTL 1). The cleaning robot 5 includes a laser sensor 1, an ultrasonic sensor 2, and a contact sensor 3, and autonomously travels by driving wheels 4 with recognition of positional relationships with other objects. The cleaning robot 5 is provided with the ultrasonic sensor 2 which detects an obstacle on its path and the contact sensor 3 which detects contact with an obstacle. The cleaning robot 5 cleans under control of a control unit so that the cleaning robot 5 can avoid obstacles detected by the sensors.